All burden values are in kg-S/m^2, here the output unit ECHAM is misleading. SO4_AS is the accumulation mode SO4 burden, SO4_CS is the coarse mode SO4 burden, SO4 is the accumulation + coarse mode SO4 burden (SO4_AS + SO4_CS), and TOTAL is the accumulation + coarse mode SO4 + SO2 burden.

Optical thicknesses:
MODE_KS -> Optical thickness of sulfate aerosols in Aitken mode
MODE_AS -> Optical thickness of sulfate aerosols in Accumulation mode
MODE_CS -> Optical thickness of sulfate aerosols in Coarse mode
COMP_SO4 -> Optical thickness of all sulfate aerosols

The variables with _825_ contain the AOD for 825nm IR radiation.
The variables without _825_ contain the AOD for 550nm solar radiation.

SO the desired variable for you would probably TAU_COMP_SO4 which contains optical thickness of all sulfate aerosols for 550nm.

Reff:
The Reff variables are again for the different modes, so ns for nucleation mode, ks for Aitken mode, as for accumulation mode and cs for coarse mode. Unfortunately we don't have a direct output for reff of the whole aerosol population. One could build a weighted average (weighting by the mass fraction of particles in each mode) to get a reff for the whole aerosol population. Nevertheless, since the the aerosol population is clearly dominated by particles in coarse mode with regard to the mass fraction one could also approximate reff by reff_cs.

So I hope this helps to understand my files and variables. I thought it might be better to upload a few more variables for the case that someone wants to do some deeper analysis. If you still have questions, please don't hesitate to ask.

